Hi Greg,

> Along with keeping tangency between lines (something I think
> I remember you discussing) would it also be possible to "weld"
> endpoints together (as apposed to joining both entire lines)such
> that you can't accidentally move a line's endpoint off it's fellow
> while editing it?

You mean with a plug-in? That would be quite difficult to do with a plug-in because you're not talking there about just a new command to add that would perform some one time calculation - you're talking there about modifying the behavior of a large number of other existing commands like all transform commands, object dragging, etc...

So I can't see how that would be implemented as a plug-in, it would need to be a modification to some of the core MoI logic.

One problem with something like that it that it's not feasible to only implement just a welder - you may want to later on move its endpoint so you also need an unwelding mechanism to manage it as well.

Then there would be quite a lot of questions to answer for other kinds of editing tools - if you tried to move a line that had an welded endpoint, what would you expect to happen, should just nothing at all happen or should everything else that was connected to that welded point also move? If nothing were to happen, then that opens some doors to some extremely confusing scenarios, like say you receive a file from someone that happens to have these "welded" pieces in them, but of course you don't know anything about that yourself so you'll get extremely confused when you try to move some things around just in the course of examining the object and you don't get any response at all.

What about other kinds of editing tools than transformations like trimming or booleans - would they fail if they would produce an object that did not include an endpoint in that particular location?

Anyway, I can certainly imagine an enormous list of side effects and concerns similar to these ones...

For the most part your best bet to make sure things touch is to have object snap on when you initially draw it. If you don't have object snap on and you're just "eyeballing" things so that they look close to one another but are not actually snapped on to one another, then that will cause problems because there the ends won't be exactly touching if you do it that way.

- Michael

Hey Michael.

Clearly I'm not intimately familiar with the ins and outs of implimenting an idea like welding endpoints together, so you'll have to forgive the idea's bluesky nature. (Clients of mine always ask for the impossible out of ignorance, so why should I be any different!)

I was imagining a tool much like join (and you're right, unweld as well) which, at the line/curve level might show a dot or highlight around the welded endpoint(s), letting you know something is going on there.

As to it's behavior, it would make sense to me to be able to move any points including the welded point independent of the other points, but not the line/curve as a whole. I imagine you could transform the line in any way as long as the welded point was the anchor and did not move. For instance, rotate around the welded point, stretch/lengthen from the welded point etc.

Now that I'm writing this I'm reminded of Illustrator and how it differentiates between independant lines/curves and continuous (after independant lines/curves are joined at their endpoints) lines/curves. The lines/curves and points are fully editable in either case and only the lines/curves behavior tells you if they are a series of lines/curves or a continuous line/curve. Illustrator also has snapping, which I was greatful to find in MoI, as it makes life SOOO much easier.

Not certain I understand the issue with the trim or boolean operations. Once a welded endpoint is trimmed off or removed due to a boolean, wouldn't it just be deleted from the resultant line?

Anyway, just food for thought.

Hi Greg,


That sounds like it would lead to the kind of potential confusion that I was mentioning earlier - say you receive a file that has a line that has one of these welded points in it, then you select that line and just try to move it off to the side - according to what you are describing here it would just remain locked in place because of its welded endpoint.

Also if I understand correctly, if you had a line that had welded endpoints on 2 sides it would then be totally locked in place and no transformation of any kind would modify it?

So like I mentioned previously, I can see quite a lot of complications with that system - also it is not easy to implement since it would involve extra checking for if a transform was allowed by every single kind of transformation tool.

An even bigger problem yet is that it would probably not even really solve a problem with people creating inaccurate drawings in the first place because you would need to do a special extra step to produce the welding, and that's not likely to be something that a beginning user is going to know a priori .

Most of the time I think that inaccurate drawings are not generated due to people moving stuff around - most of the time I think they are created because things are not snapped together using object snaps when they are initially drawn. I suspect that a welding system as you're describing wouldn't really help with this type of problem.

It could be useful for other things, but since it would involve a kind of extra layer of checking on the part of numerous transformation commands, that's kind of an indication that it's a quite complex system. That kind of complexity can lead to a lot of various side effects, like that one I mentioned before about being surprised when receiving a file that behaved oddly when you tried to edit it since you were not aware of this big welded system being set up is only one.

Right now I'd have to say that it seems pretty impractical to try and implement that.

I have thought before about having a different system for building geometry, one more similar to how polygon mesh geometry is constructed where you have things like faces that share a common vertex point. But overall that's a pretty different kind of a system than how the geometry library that MoI uses is based on.

So there's definitely some interesting possibilities with the idea, but it just does not seem likely to be something that would be "implementable" within MoI, at least with with its current regular geometry. It could be possible in the future with a different type of polygon mesh entity type that was a kind of different class of object, like with its own separate data structures and different code paths for operating on them. That's a big task too though.

- Michael

how about an area selection that lets you choose which way to move depending on what you want to weld. (i.e. pick a base or point as an anchor and shift the selected points to that location?) I think it could be a one time operation that would not require an infinite zoom to see minor spaces and would work just like a snap command...just my 5 cents.

-Luis

Hi Luis,

> how about an area selection that lets you choose which way to
> move depending on what you want to weld. (i.e. pick a base or
> point as an anchor and shift the selected points to that location?) <...>

I'm not sure if I understand properly, but if you want to be able to zoom in to a particular point using snaps to set the point to zoom to, there is a "Zoom Area" tool available in the toolbar that's at the bottom of each viewport which will do that:



- Michael

Maybe the wording didn't quite work this time.

I meant being able to select some points around an area (the same way the you can area select points when "show points" is on) and then from that selection choose the point to which all other selected points automatically snap to without having to move each point to that particular selected snap point or anchor. Let me know if that makes more sense.

--Luis

hmmm...maybe I should say collapse to instead....

You don't want to do that with Nurbs modelling. You will end up with distorted surfaces. Best to just delete the points you don't need.

Hi Luis, right now you can use the Align tool a couple of times to do that - Align will line up one dimension (like horizontal or vertical in the viewport you are using) to the specific point that you pick.

I do plan on adding in some more tools for point editing in the future though, and some method to set all selected points to one value would probably be a part of that.

It is not good to collapse points on the same curve down to each other though.

- Michael

agreed, I was focusing more on snapping multiple end points from different curves to one location with a simple command rather than having to do it one by one or using the align tool multiple times. But alas, it can be done with a simple align tool like Michael says...

I would find it quite useful though if there was a way to tell if two or more curves actually cross through a common point such that in case of a curve adjustments any separation would be visible. Obviously, a tool that catches and fixes those gaps during curve control point adjustments would be of even greater use. I don't quite know how to do that yet in Moi...but it kinda goes along with the welding question...

-Luis

Hi Luis, also in the future I think I'm going to adjust the way the Transform > Align command works when only control points are selected.

The regular options for stuff like left-side / center / right-side don't really do anything different for points so I could do something like simplify the options to just horizontal and vertical and then that would make it easier to also put in a "collapse" option for it as well.

re: Weld - welding curves in MoI is handled by the Join command, it can join 2 curves that touch at a common end into a longer curve made up of multiple segments. But it's focused more on making closed curves which is why it only tries to join 2 curves at any one endpoint together. Joining 3 or more curves makes for a type of branching structure and not just a simple closed curve.

At some point in the future I'd like to make it possible for a history function to work for making more easily editable branched structures, but that's probably quite a ways out.

- Michael

Hi,

i know this is probably more of a mathematical problem than not, but it would be awesome if you there was a way to have "on-curve" anchored snap points such that any other curve that attaches to it must pass through that point no matter what adjustments are made made afterwards (kinda like linking points on curves).

Usually if I draw a curve through points and leave it alone it works wonderfully, but any time control points are adjusted on that curve there is a likely chance that it no longer touches upon the original set of points and/or snaps used to create it.

Obviously this may affect surrounding control points to account for the "must pass-through point" requirement, but this would ensure they always touch or intersect at the desired location.

Do you think there's is such a possibility? or is there a way to do this currently?

Thanks,

Luis

What about an "align to curve" command, that can give a lot more flexibility!

Hi Luis,

> Do you think there's is such a possibility? or is there a
> way to do this currently?

There is no way to do that currently, but in the future I do want to make it possible to edit the original "through points" when you turn on edit points for a curve that was constructed by that method.

I'm kind of waiting to get an extended object properties dialog together before having that, I can then put an option on that dialog that will let you control some aspects of what points are actually shown when you show edit points (either the actual curve control points, or the actual input points), and also modify some things like how many points are used for circles.

- Michael

Relatively new to MoI but find it very nice to use and powerful.

I've been flowing objects onto curved surfaces and then using diff to subtract but this does not always work correctly in V3. V3 often removes unintended bits of the base object and can leave a very weird looking result.

To get around this I've been importing the model into V2 and then the diff works as expected.

Cheers - Jim

Hi Jim, do you have some example files with the problematic booleans that you could post here or e-mail to me at moi@moi3d.com so I could check them out?

One thing that can help is to avoid making a flow where the deformed result just barely skims right along some overlapping surface area on the target object, make the cutting object sunken down a little bit into the base plane so that it pushes some distance through the other object rather than just barely skimming it.

- Michael

Hi Michael, I've tried with my latest model and that works fine in V3 and have also tried to go back to what I thought I did but haven't managed to get it to fail again.

Come to think of it the subtracted objects would have been very close to at least one surface so I expect your comment could explain what went wrong.

In future I'll keep the files for you.

Cheers - Jim